Scema:
Person(pid:int,
name:char(20),
predecessor:int -> Person.pid
)
Example Table:
pid, name, predecessor
0, 'abc', NULL
1, 'bcd', 0
2, 'cde', 1
3, 'efg', NULL
4, 'fgh', 3
How do i find all successors of a Person 'abc'?
Desired Ouput:
name
'bcd'
'cde'
Many Thanks!
You can do this by generating all the ancestors and then filtering them out. The following is an example for your data:
with recursive cte(pid, lev, ancestor) as (
select pid, 0, predecessor
from person p
union all
select cte.pid, lev + 1, p.predecessor
from person p join
cte
on p.pid = cte.ancestor
)
select p2.name
from cte join
person p1
on cte.ancestor = p1.pid join
person p2
on cte.pid = p2.pid
where p1.name = 'abc';
Here is a SQL Fiddle.
Just generate the rows you need (not all ancestors for all rows) in a recursive CTE:
with recursive cte as (
select p.pid, p.name, 1 AS lvl
from person a
join person p ON p.predecessor = a.pid
where a.name = 'abc'
union all
select p.pid, p.name, c.lvl + 1
from cte c
join person p ON p.predecessor = c.pid
)
select name
from cte
order by lvl;
SQL Fiddle.
Aside: You don't want to use char(20). Just use text.
Related
Here is entry's hierarchy.
_________Milky Way (30)________
/ | \
Alpha(10) Beta(20) Delta(null)
/ \ |
Mars(7) Jupiter(3) Delta-child(44)
Parents value is a sum of it's children's values.
Ex.
Alpha = Mars + Jupiter = 7 + 3 = 10
Milky Way = Alpha + Beta + Delta = 10 + 20 + null = 30
The task: recalculate parents up to the root in case any child is updated. Let's even simplify the task: select all entries up to the root with recalculated values.
Imagine that Mars is updated. Now Mars value is 2.
_________Milky Way (?)________
/ | \
Alpha(?) Beta(20) Delta(null)
/ \ |
Mars(2) Jupiter(3) Delta-child(44)
It means that all parents should be updated:
Alpha = Mars + Jupiter = 2 + 3 = 5
Milky Way = Alpha + Beta + Delta = 5 + 20 + null = 25.
Note: Delta -> Delta-child coupling is broken and it's fine. It can happen lets leave it out of scope here. 've added this sample just to be sure that it won't be counted during calculation as hierarchy can be huge enough and tehre is no task to recalculate all children leaf, just parents up to the root.
As a result of some "select .. from hierarchy.."
I'd like to receive recalculated parents' values.
Ex.
id
name
value
1
Milky Way
25
2
Alpha
5
Code samples with already updated Mars (sqlfiddle links are below):
Schema
CREATE TABLE hierarchy
(
id int4,
parent_id int4,
name varchar(255),
value int4
);
Values
insert into hierarchy
values
(1, null, 'Milky Way', 30),
(2, 1, 'Alpha', 10),
(3, 1, 'Beta', 20),
(4, 1, 'Delta', null),
(5, 2, 'Mars', 2),
(6, 2, 'Jupiter', 3),
(7, 4, 'Delta-child', 44);
What I have tried:
I was able to list all leafs which should be used in calculation
sqlfiddle 1
WITH RECURSIVE cte AS (
SELECT h1.id, h1.parent_id, h1.name , h1.value from hierarchy h1
where h1.id = 5
UNION
SELECT h2.id, h2.parent_id, h2.name , h2.value from hierarchy h2
JOIN cte cte ON (cte.parent_id = h2.parent_id or cte.parent_id = h2.id )
where cte.id != h2.id
) select * from cte
order by id
When I tried to sum values, query goes in infinite loop for some reason
sqlfiddle 2
WITH RECURSIVE cte AS (
SELECT h1.id, h1.parent_id, h1.name , h1.value from hierarchy h1
where h1.id = 5
UNION
SELECT h2.id, h2.parent_id, h2.name , (h2.value + cte.value) as value from hierarchy h2
JOIN cte cte ON (cte.parent_id = h2.parent_id or cte.parent_id = h2.id )
where cte.id != h2.id
) select * from cte
order by id
There is one more query that I have tried, unfortunately it doesn't count sibling of parents.
sqlfiddle 3
WITH RECURSIVE cte AS (
SELECT h1.id, h1.parent_id, h1.name , h1.value from hierarchy h1
where h1.parent_id = (select parent_id from hierarchy where id = 5)
UNION
SELECT h2.id, h2.parent_id, h2.name , cte.value as value from hierarchy h2
JOIN cte cte ON (cte.parent_id = h2.parent_id or cte.parent_id = h2.id )
where cte.id != h2.id
) select id, parent_id, name, sum(value) from cte
group by id, parent_id, name
order by id
I'd appreciate any assistance. :-)
It took me a while, but good work on your trials.
What i did is that I split the problem in parts.
go down the hierarchy with the recursive query
with recursive base_qry as (
select id,
parent_id,
value,
ARRAY[id] as id_array
from hierarchy
union all
select h.id,
h.parent_id,
h.value,
id_array || h.id as id_array
from hierarchy h join base_qry b on h.parent_id = b.id and h.value is not null
)
Understand the nodes affected filtering the last id of the array containing all the nodes with id_array[array_length(id_array,1)] = 5
nodes_affected as (
select * from base_qry
where id_array[array_length(id_array,1)] = 5
order by array_length(id_array,1) desc
LIMIT 1)
Find all the tree breanches than contribute to changed nodes (check here the filter for node id=5)
all_combinations as (
select b.id, b.parent_id, b.value, b.id_array from
base_qry b join nodes_affected n
on ARRAY[n.id_array] && ARRAY[b.id_array]
where (b.id_array[array_length(b.id_array,1)] = 5
or b.id_array #> ARRAY[5] = false)
)
aggregating up
select id_array[1]::int id, sum(value)
from all_combinations where id not in (select parent_id from all_combinations where parent_id is not null)
group by id_array[1]::int
order by 1
Whole query
with recursive base_qry as (
select id,
parent_id,
value,
ARRAY[id] as id_array
from hierarchy
union all
select h.id,
h.parent_id,
h.value,
id_array || h.id as id_array
from hierarchy h join base_qry b on h.parent_id = b.id and h.value is not null
),
nodes_affected as (
select * from base_qry
where id_array[array_length(id_array,1)] = 5
order by array_length(id_array,1) desc
LIMIT 1),
all_combinations as (
select b.id, b.parent_id, b.value, b.id_array from
base_qry b join nodes_affected n
on ARRAY[n.id_array] && ARRAY[b.id_array]
where (b.id_array[array_length(b.id_array,1)] = 5
or b.id_array #> ARRAY[5] = false)
)
select id_array[1]::int id, sum(value)
from all_combinations where id not in (select parent_id from all_combinations where parent_id is not null)
group by id_array[1]::int
order by 1
;
Start from the leafs and traverse all the nodes the leaf contributes to up the hierachy. Then just sum all contributions to a node.
WITH RECURSIVE cte AS (
SELECT id, parent_id, value
FROM hierarchy h1
WHERE not exists (select 1 from hierarchy h2 where h2.parent_id = h1.id)
UNION ALL
SELECT h.id, h.parent_id, case when h.value is null then 0 else cte.value end
FROM hierarchy h
JOIN cte ON (cte.parent_id = h.id)
)
select h.id, h.name, v.value
from (
select id, sum(value) as value
from cte
group by id
) v
join hierarchy h on h.id = v.id
order by h.id;
db<>fiddle
You can use a recursive CTE to get all nodes and their paths, and then for every non-leaf node in hierarchy, you can join the CTE back to hierarchy on the condition that the current hierarchy row id exists in the path and sum the values:
with recursive cte(id, p, n, v, t) as (
select h.*, concat('[', h.id::text) from hierarchy h where h.parent_id is null
union all
select h.id, h.parent_id, h.name, h.value, concat(c.t, ', ', h.id)
from cte c join hierarchy h on c.id = h.parent_id
)
select h.id, sum(c.v)
from hierarchy h join cte c on c.id != h.id and exists (select 1 from jsonb_array_elements(concat(c.t, ']')::jsonb) v where v.value::text = h.id::text)
group by h.id order by h.id
Output:
id sum
1 79
2 5
4 44
How do I loop through all children and update one column for all the nodes? For example if I am on the parent level with column "OrganisationLevelID". If I update the "OrganisationLevelID" on the parent row it should propogate to the children hence all children of parent as well as the childrens' children should then have the same value in "OrganisationLevelID".
I have the following cte:
WITH cte as
(select h.Name, h.ID, h.OrganisationLevelID, h.parentId
From organisations h
WHERE ID = '3eea8c17-1bfd-46d5-9ea9-2d11652d23a4'
UNION ALL
select p.Name, p.ID, p.OrganisationLevelID, p.parentId
FROM organisations p
INNER JOIN cte c ON c.Id = p.parentId)
SELECT * FROM cte
This gets the parent child hierarchy and works fine.
How do I update the children values so that they all have the parent's "OrganisationLevelID"?
WITH cte as
(select h.Name, h.ID, h.OrganisationLevelID, h.parentId
From organisations h
WHERE ID = '3eea8c17-1bfd-46d5-9ea9-2d11652d23a4'
UNION ALL
select p.Name, p.ID, p.OrganisationLevelID, p.parentId
FROM organisations p
INNER JOIN cte c ON c.Id = p.parentId),
cteupdate as(**Some magic here**)
If you're looking for updating actual records in the Organisations table, I believe you can try this:
;WITH cte
AS (
SELECT h.Name
, h.ID
, h.OrganisationLevelID
, h.parentId
FROM organisations h
WHERE ID = '3eea8c17-1bfd-46d5-9ea9-2d11652d23a4'
UNION ALL
SELECT p.Name
, p.ID
, c.OrganisationLevelID -- note that I changed the alias from "p" to "c" to use the parent's value
, p.parentId
FROM organisations p
INNER JOIN cte c
ON c.Id = p.parentId
)
UPDATE org
SET OrganisationLevelID = cte.OrganisationLevelID
FROM organisations org
INNER JOIN cte
ON org.id = cte.id
You can use the below sample code to see what will happen, specifically the value in orgValueId from the parent row will "propagate" to all of its children and descendants:
create table #t (id int, parentid int, orgValueId varchar(10));
insert into #t values (1, null, 'x'), (2, 1, 'o'), (3, 1, 'm'), (4, 2, 'v'), (5, 3, 'p');
select *
from #t;
with cte as (
select id
, orgValueId
from #t
where parentid is null
union all
select t.id
, c.orgValueId
from cte c
inner join #t t on c.id = t.parentid)
update t
set orgValueId = c.orgValueId
from #t t
inner join cte c
on t.id = c.id;
select *
from #t;
Given the following PostgreSQL table:
items
integer id
integer parent_id
string name
unique key on [parent_id, name]
parent_id is null for all root nodes
Currently I build the sql query manually, doing a join for every path element. But is seems quite ugly to me and of course it limits the possible depth.
Example:
path: holiday,images,spain
SELECT i3.*
FROM items AS i1
, items AS i2
, items AS i3
WHERE i1.parent_id IS NULL AND i1.name = 'holiday'
AND i2.parent_id=i1.id AND i2.name = 'images'
AND i3.parent_id=i2.id AND i3.name = 'spain'
I wonder if there's a better way, probably using CTE?
You can see how my current code works and what the expected output is here:
http://sqlfiddle.com/#!1/4537c/2
update2 here's a function, it peforms well, because search goes only within the path, starting from parent:
create or replace function get_item(path text[])
returns items
as
$$
with recursive cte as (
select i.id, i.name, i.parent_id, 1 as level
from items as i
where i.parent_id is null and i.name = $1[1]
union all
select i.id, i.name, i.parent_id, c.level + 1
from items as i
inner join cte as c on c.id = i.parent_id
where i.name = $1[level + 1]
)
select c.id, c.parent_id, c.name
from cte as c
where c.level = array_length($1, 1)
$$
language sql;
sql fiddle demo
update I think you can do recursive traversal. I've written sql version of this, so it's a bit messy because of cte, but it's possible to write a function:
with recursive cte_path as (
select array['holiday', 'spain', '2013'] as arr
), cte as (
select i.id, i.name, i.parent_id, 1 as level
from items as i
cross join cte_path as p
where i.parent_id is null and name = p.arr[1]
union all
select i.id, i.name, i.parent_id, c.level + 1
from items as i
inner join cte as c on c.id = i.parent_id
cross join cte_path as p
where i.name = p.arr[level + 1]
)
select c.*
from cte as c
cross join cte_path as p
where level = array_length(p.arr, 1)
sql fiddle demo
or you can build path for all of the elements using recursive cte for that and accumuate your path into array or string:
with recursive cte as (
select i.id, i.name, i.parent_id, i.name::text as path
from items as i
where i.parent_id is null
union all
select i.id, i.name, i.parent_id, c.path || '->' || i.name::text as path
from items as i
inner join cte as c on c.id = i.parent_id
)
select *
from cte
where path = 'holiday->spain->2013';
or
with recursive cte as (
select i.id, i.name, i.parent_id, array[i.name::text] as path
from items as i
where i.parent_id is null
union all
select i.id, i.name, i.parent_id, c.path || array[i.name::text] as path
from items as i
inner join cte as c on c.id = i.parent_id
)
select *
from cte
where path = array['holiday', 'spain', '2013']
sql fiddle demo
This should perform very well, as it eliminates impossible paths immediately:
WITH RECURSIVE cte AS (
SELECT id, parent_id, name
,'{holiday,spain,2013}'::text[] AS path -- provide path as array here
,2 AS lvl -- next level
FROM items
WHERE parent_id IS NULL
AND name = 'holiday' -- being path[1]
UNION ALL
SELECT i.id, i.parent_id, i.name
,cte.path, cte.lvl + 1
FROM cte
JOIN items i ON i.parent_id = cte.id AND i.name = path[lvl]
)
SELECT id, parent_id, name
FROM cte
ORDER BY lvl DESC
LIMIT 1;
Assuming you provide a unique path (only 1 result).
->SQLfiddle demo
Too late to post my answer (very equivalent to Roman's and Erwin's) But an improvement on the table definition instead:
CREATE TABLE items
( id integer NOT NULL PRIMARY KEY
, parent_id integer REFERENCES items(id)
, name varchar
, UNIQUE (parent_id,name) -- I don't actually like this one
); -- ; UNIQUE on a NULLable column ...
INSERT INTO items (id, parent_id, name) values
(1, null, 'holiday')
, (2, 1, 'spain'), (3, 2, '2013')
, (4, 1, 'usa'), (5, 4, '2013')
;
I have got two tables as following
Table Person
Id Name
1 A
2 B
3 C
4 D
5 E
Table RelationHierarchy
ParentId ChildId
2 1
3 2
4 3
This will form a tree like structure
D
|
C
|
B
|
A
ParentId and ChildId are foreign keys of Id column of Person Table
I need to write SQL that Can fetch me Top Level Parent i-e Root. Can anyone suggest any SQL that can help me accomplish this
You can use recursive CTE to achieve that:
DECLARE #childID INT
SET #childID = 1 --chield to search
;WITH RCTE AS
(
SELECT *, 1 AS Lvl FROM RelationHierarchy
WHERE ChildID = #childID
UNION ALL
SELECT rh.*, Lvl+1 AS Lvl FROM dbo.RelationHierarchy rh
INNER JOIN RCTE rc ON rh.CHildId = rc.ParentId
)
SELECT TOP 1 id, Name
FROM RCTE r
inner JOIN dbo.Person p ON p.id = r.ParentId
ORDER BY lvl DESC
SQLFiddle DEMO
EDIT - for updated request for top level parents for all children:
;WITH RCTE AS
(
SELECT ParentId, ChildId, 1 AS Lvl FROM RelationHierarchy
UNION ALL
SELECT rh.ParentId, rc.ChildId, Lvl+1 AS Lvl
FROM dbo.RelationHierarchy rh
INNER JOIN RCTE rc ON rh.ChildId = rc.ParentId
)
,CTE_RN AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY r.ChildID ORDER BY r.Lvl DESC) RN
FROM RCTE r
)
SELECT r.ChildId, pc.Name AS ChildName, r.ParentId, pp.Name AS ParentName
FROM CTE_RN r
INNER JOIN dbo.Person pp ON pp.id = r.ParentId
INNER JOIN dbo.Person pc ON pc.id = r.ChildId
WHERE RN =1
SQLFiddle DEMO
EDIT2 - to get all persons change JOINS a bit at the end:
SELECT pc.Id AS ChildID, pc.Name AS ChildName, r.ParentId, pp.Name AS ParentName
FROM dbo.Person pc
LEFT JOIN CTE_RN r ON pc.id = r.CHildId AND RN =1
LEFT JOIN dbo.Person pp ON pp.id = r.ParentId
SQLFiddle DEMo
I've used this pattern to associate items in a hierarchy with the item's root node.
Essentially recursing the hierarchies maintaining the values of the root node as additional columns appended to each row. Hope this helps.
with allRows as (
select ItemId, ItemName, ItemId [RootId],ItemName [RootName]
from parentChildTable
where ParentItemId is null
union all
select a1.ItemId,a1.ItemName,a2.[RootId],a2.[RootName]
from parentChildTable a1
join allRows a2 on a2.ItemId = a1.ParentItemId
)
select * from allRows
To find all top-level parents, use a query like:
select p.Name
from Person p
where not exists
(select null
from RelationHierarchy r
where r.ChildId = p.Id)
SQLFiddle here.
To find the top-level parent of a specific child, use:
with cte as
(select t.ParentId TopParent, t.ChildId
from RelationHierarchy t
left join RelationHierarchy p on p.ChildId = t.ParentId
where p.ChildId is null
union all
select t.TopParent TopParent, c.ChildId
from cte t
join RelationHierarchy c on t.ChildId = c.ParentId)
select p.name
from cte h
join Person p on h.TopParent = p.Id
where h.ChildId=3 /*or whichever child is required*/
SQLFiddle here.
Try this.
The recursive CTE will find the person and walk up the hierarchy until it finds no parent.
-- This CTE will find the ancestors along with a measure of how far up
-- the hierarchy each ancestor is from the selected person.
with ancestor as (
select ParentId as AncestorId, 0 as distance
from RelationHierarchy
where CHildId = ?
union all
select h.ParentId, a.distance + 1
from ancestor a inner join RelationHierarchy rh on a.AncestorId = rh.ChildId
)
select AncestorId
from ancestor
where distance = (select max(distance) from ancestor)
Something like this will work for above example:
SELECT ParentId FROM RelationHierarchy
WHERE ParentId NOT IN (SELECT CHildId FROM RelationHierarchy)
The only way you can do this in "standard" SQL is to assume a maximum depth for the tree, and then do joins for each level. The following gets the top level id:
select rh1.ChildId,
coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid) as topLevel
from RelationshipHierarchy rh1 left outer join
RelationshipHierarchy rh2
on rh1.parentId = rh2.childId left outer join
RelationshipHierarchy rh3
on rh2.parentId = rh3.childId left outer join
RelationshipHierarchy rh4
on rh3.parentId = rh4.childId;
If you want the name, you can just join it in:
select rh1.ChildId,
coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid) as topLevel,
p.name
from RelationshipHierarchy rh1 left outer join
RelationshipHierarchy rh2
on rh1.parentId = rh2.childId left outer join
RelationshipHierarchy rh3
on rh2.parentId = rh3.childId left outer join
RelationshipHierarchy rh4
on rh3.parentId = rh4.childId left outer join
Person p
on p.id = coalesce(rh4.parentid, rh3.parentid, rh2.parentid, rh1.parentid);
Get all top parents using path
path format: rootId/.../parentId/nodeId/
select t1.path from nodes t1 inner join nodes t2
on t1.path like t2.path+'%'
group by t1.path
having len(t1.path)-len(replace(t1.path, '/', ''))
=min(len(t2.path)-len(replace(t2.path, '/', '')))
Give this a go:
select id,name
from person p
where not exists
(
select 1
from relationhierarchy r
where r.childid= p.id
)
and exists
(
select 1
from relationhierarchy r
where r.parentid= p.id
)
It is not enough to just see if a child id exists as in your example E is present in the person table but not in the relationshiphierarchy table.
WITH CTE_MyTable AS (
SELECT Id, ParentId, NULL As RootParent, 1 As Lvl
FROM dbo.Ministry
UNION ALL
SELECT a.id, b.ParentId, a.ParentId As RootParent, Lvl + 1
FROM CTE_MyTableAS a INNER JOIN
dbo.MyTableAS b ON a.ParentId = b.Id
)
, CTE_Ministry_RN AS (
SELECT Id, RootParent, ROW_NUMBER() OVER (PARTITION BY Id ORDER BY Lvl DESC) RN
FROM CTE_Ministry
)
SELECT Id, ISNULL(RootParent, Id) As RootParent
FROM CTE_Ministry_RN
WHERE RN = 1
ID parent_id name
---------------------
1 2 first
2 4 second
3 3 third
4 5 fourth
5 - fifth
Ancestors list of first should be (2, 4, 5)
with name_tree as (
select id, parent_id, name
from the_unknown_table
where id = 1 -- this is the starting point you want in your recursion
union all
select c.id, c.parent_id, c.name
from the_unknown_table c
join name_tree p on p.parent_id = c.id -- this is the recursion
)
select *
from name_tree
where id <> 1; -- exclude the starting point from the overall result
SQLFiddle: http://sqlfiddle.com/#!3/87d0c/1
You can use something like this:
with parents as
(
select ID, parent_ID
from t
where parent_ID is not null
union all
select p.ID, t.parent_ID
from parents p
inner join t on p.parent_ID = t.ID
and t.parent_ID is not null
and t.ID <> t.parent_ID
)
select *
, parents = '(' + stuff
(
(
select ', ' + cast(p.parent_ID as varchar(100))
from parents p
where t.ID = p.ID
for xml path('')
), 1, 2, ''
) + ')'
from t
order by ID
SQL Fiddle with demo.
This combines two very common T-SQL techniques - using a CTE to get a hierarchy and using FOR XML PATH to get a CSV list.